Fenton's reagent, i.e., hydrogen peroxide, sulfuric acid, and iron 2+ cation, produces a solution of hydroxyl radicals. This solution is a strong oxidizer and is commonly used in environmental cleanups to decompose toxins and contaminants. Although in iron/hydrogen peroxide systems some have measured the loss of hydrogen peroxide as an indicator for hydroxyl radical formation, this approach is not entirely satisfactory because not all of the peroxide degraded is necessarily converted to hydroxyl radicals, and the complexity of the reaction often leads to the formation of a variety of species. Thus, it is desirable to identify a method for the qualitative determination of the presence of hydroxyl radicals in complex reaction systems.
Previous methods developed for the qualitative detection of hydroxyl radicals have often depended on the addition of chemical probes, such as salicylic acid, and correlating the resulting hydroxylated reaction products as an indirect measurement of the presence and level of hydroxyl radicals. In the presence of other hydroxyl radical scavenging and reacting chemicals, the addition of a chemical probe to the reaction mixture results in competition for the hydroxyl radicals and the possibility of interacting byproduct reactions. In addition, the possibility of multiple hydroxylated products often makes the detection of hydroxyl radicals complicated. Electron spin resonance can be used to detect hydroxyl radicals by measuring the electron paramagnetic spectrum of a spin adduct hydroxyl radical derivative after spin trapping. However, this requires expensive instrumentation and is not easy to carry out because of instability of hydroxyl radical spin adducts. Thus, there is a need to identify an improved method of detecting hydroxyl radicals that is easier to implement.